Psoriasis | Causes & Risk Factors


What causes psoriasis?

Psoriasis starts with the immune system. Your immune system usually protects the body against infection and disease by attacking bacteria and viruses. However, when you have psoriasis, your T cells, a kind of white blood cells that are part of the immune system, mistakenly attack your skin cells instead. Your body then produces other immune system responses, leading to swelling and rapid production of skin cells. Psoriasis tends to run in families and it usually appears between 10 and 45 years of age.

People who have psoriasis may experience periods of time without any symptoms. Other times, psoriasis will "flare up" (get worse). Certain things that can cause the psoriasis to get worse include:

  • Infections (such as strep throat and the common cold)
  • Diseases that weaken the immune system
  • Stress
  • Certain medicines (such as beta-blockers for high blood pressure and drugs used to prevent malaria)
  • Skin irritations
  • Cold weather
  • Smoking

Written by editorial staff

Reviewed/Updated: 04/14
Created: 07/95